The curing of monomeric materials to produce thermoset resins is well known in the art. In general, the polymerizable monomers have at least one and customarily more than one reactive group which serves as a site for the curing or crosslinking polymerization to produce the cured insoluble solids which are typically highly crosslinked. There are some polymerizable monomeric materials wherein the active sites are such that the monomer will cure upon application of energy, e.g., heat or high intensity UV light. In many if not most cases, however, a curing agent is necessary to allow the curing or crosslinking reaction to proceed at an acceptable rate. The curing agents are catalytic or are stoichiometric relative to the resin to be crosslinked. The stoichiometric curing agents, i.e., agents which are employed in substantial quantities relative to the quantity of the resin, are the more commonly utilized and are typically multi-functional polymerizable compounds having a plurality of reactive groups capable of participating in crosslinking reactions. A mixture of a thermoset resin and a curing agent is then cured by application of heat, with or without the presence of an accelerator added to obtain a more acceptable curing rate.
Thermoset resins containg arylcyclobutene moieties, especially benzocyclobutene moieties, are known in the art. A series of U.S. Patents to Kirchhoff, illustrated by U.S. Pat. No. 4,540,763, describes the production and curing of a large number of benzocyclobutene derivatives wherein the benzocyclobutene moieties are connected by linking groups substituted on a carbon atom of a six-membered ring of the arylcyclobutene ring system. A copending U.S. patent application Ser. No. 364,275, filed June 12, 1989, describes and claims a class of arylcyclobutenecarboxylate esters wherein the ester group which serves to connect the arylcyclobutene moiety to the remainder of the molecule is substituted on a carbon atom of a four-membered ring of the aryclocyclobutene ring system. Also claimed are the self-cured products obtained therefrom.
It would be of advantage to provide a novel class of thermosetting resin compositions which cure at an acceptable rate without the requirement for accelerators to produce highly crosslinked, insoluble solids having good properties of strength and rigidity.